During the production life of an oil or gas well, the production zone within the well is typically subjected to numerous treatments. Corrosion of metallic surfaces, such as downhole tubulars, during such treatments is not uncommon and is evidenced by surface pitting, localized corrosion and loss of metal. Metallic surfaces subject to such corrosion are carbon steels, ferritic alloy steels, and high alloy steels including chrome steels, duplex steels, stainless steels, martensitic alloy steels, austenitic stainless steels, precipitation-hardened stainless steels and high nickel content steels.
Further, aqueous fluids, such as those used in drilling and completion, have a high salt content which causes corrosion. Gases, such as carbon dioxide and hydrogen sulfide, also generate highly acidic environments to which metallic surfaces become exposed. For instance, corrosion effects from brine and hydrogen sulfide are seen in flow lines during the processing of gas streams. The presence of methanol, often added to such streams to prevent the formation of undesirable hydrates, further often increases the corrosion tendencies of metallic surfaces.
Further, naturally occurring and synthetic gases are often conditioned by treatment with absorbing acidic gases, carbon dioxide, hydrogen sulfide and hydrogen cyanide. Degradation of the absorbent and acidic components as well as the generation of by-products (from reaction of the acidic components with the absorbent) results in corrosion of metallic surfaces.
The use of corrosion inhibitors during well treatments to inhibit the rate of corrosion on metal components and to protect wellbore tubular goods is well known. Commercial corrosion inhibitors are usually reaction mixtures or blends that contain at least one component selected from nitrogenous compounds, such as amines, acetylenic alcohols, mutual solvents and/or alcohols, surfactants, heavy oil derivatives and inorganic and/or organic metal salts.
Many conventional corrosion inhibitors used to reduce the rate of acid attack on metallic surfaces and to protect the tubular goods of the wellbore are becoming unacceptable in oilfield treatment processes. For instance, many conventional corrosion inhibitors have become unacceptable due to environmental protections measures that have been undertaken. In some instances, such as in stimulation processes requiring strong acids, high temperatures, long duration jobs and/or special alloys, the cost of corrosion inhibitors may be so high that it becomes a significant portion of total costs.
Efforts have been undertaken to find alternative corrosion inhibitors which are cost effective and which are capable of controlling, reducing or inhibiting corrosion.